The invention pertains to low speed aircraft using lighter-than-air gas within an aerodynamically shaped airfoil envelope.
It has long been recognized that an aircraft using an airfoil envelope filled with a lighter-than-air gas can be used in a low speed aircraft, and reference is made to U.S. Pat. Nos. 1,424,491, 1,679,565, 1,841,815 and 1,845,251. Such aircraft utilizes the airfoil configuration of the gas envelope to provide additional lift, as well as confine the gas. However, such aircraft has not proven practical for a variety of reasons, and one of the greatest deterrents to further development of this type of aircraft lies in the inability to construct the airfoil envelope in an economical, lightweight and relatively low cost manner having sufficient strength to withstand rugged use.
Previously designed aircraft using a gas filled envelope were either too expensive to manufacture to be economically practical, of insufficient strength, or the construction of the envelope did not have the necessary characteristics to achieve both the advantage of the buoyancy of the gas, and the lifting characteristics of the airfoil.